Well tool retrieving apparatus



y 23, 1957 H. L. MCGILL 3,321,018

WELL TOOL RETRIEVING APPARATUS Filed Oct. 7, 1964 2 SheetsSheet 1 23 Mi //4 //7 M6 INVENTOR. w llamrrd L. can! May 23, 1967 Filed Oct. 7, 1964 H. L. MCGILL WELL TOOL RETRIEVING APPARATUS 2 Sheets-Sheet 2 United States Patent 3,321,018 WELL TQUL RETRIEVING APPARATUS Howard L. McGill, Houston, Tern, assignor by means assignments, to Sclilumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed Oct. 7, 1964, Ser. No. 402,102 9 Claims. (Cl. 166-435) This invention relates to apparatus for retrieving well tools within a well bore; and, more particularly, to running-in and retrieving overshots adapted for use With apparatus for packing-off a well bore.

In conducting such well completion operations as acidizing, cementing, or fracturing, a full-opening well packer dependently coupled from a tubing string is employed to pack-off the formation interval to be treated from the remainder of the well bore thereabove. Where more than one formation interval is to be completed, it is usually customary to releasably couple beneath the packer a selectively operable, retrievable bridge plug to pack-off the well bore at the lower limit of the formation interval being treated to prevent treating fluids from flowing into the other formations therebelow. The releasable couplings generally employed for this are comprised of a male coupling or fishing neck on the upper end of the bridge plug mandrel which is selectively connected through cooperatively arranged J-pins and J-slots to a tubular female coupling member or overshot dependently coupled beneath the packer.

The bridge plug is first set at a particular depth and the packer is disconnected therefrom and moved on up the well bore and set where desired. Treating fluids are then pumped downwardly at high pressure through the tubing and packer and introduced into the isolated formation through appropriately placed perforations in the casing. After the well-completion operation has been concluded, the packer is unseated and then shifted downwardly and re-coupled to the bridge plug. The bridge plug is then unseated by properly manipulating its mandrel and either moved to a new position or else removed entirely from the well.

It is not at all uncommon, however, for a substantial quantity of heavy loose materials to settle on top of a bridge plug during a treating operation. Subsequently, when it comes time to retrieve the bridge plug, it is often found that so much debris has accumulated that the overshot beneath the packer can not be re-engaged with the fishing neck on the bridge plug. In such instances, it is customary to attempt to wash-over the accumulated debris so that the releasable coupling members may again be re-connected. Such washing-over is typically carried out by circulating fluids through the tubing as it is being rotated so that cutting teeth around the lower end of the overshot can cut away the accumulated debris.

It will be seen, however, that once the J-pins enter the open upper end of the I-slots in the fishing neck, the overshot can no longer be rotated relative thereto. Then, if the overshot can not be forced downwardly through the remaining debris far enough to enable the I-pins to be shifted into the closed portions of the I-slots to allow the bridge plug to be retrieved, the overshot can only be reciprocated or spudded with the hope that it will chip away a sutficient amount of debris to enable it to move on downwardly. Where debris has accumulated and hardened around the upper end of the bridge plug, however, it is usually necessary to remove the tubing string, packer and overshot; attach a drilling bit and then relower the tubing string and bit to drill through the debris and bridge plug.

Accordingly, it is an object of the present invention to provide new and improved overshots which may be con- 3,321,018 Patented May 23, 1957 tinually rotated to cut away accumulated debris until they are positively re-engaged with a fishing neck of a bridge plug.

This and other objects of the present invention are accomplished by movably mounting on an upright member of a well tool a second member adapted to be received within an overshot and operatively coupling the two members together in such a manner that after the overshot has become engaged with the second member, the overshot can still be rotated until it has become securely connected to the well tool member.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of one embodiment of an overshot and a fishing neck of the present invention; and

FIG. 2 illustrates a typical bridge plug as it is being released by an overshot such as depicted in FIG. 1.

Turning now to FIG. 1, a tubular overshot is shown in position on a fishing neck 101 eXtendingfrom the upper end of an upright tool body such as the mandrel 102 of a conventional bridge plug (not shown). As is customary, lateral ports 103 are provided through the mandrel 102 at the upper end of an axial bore 104 extending through the mandrel. A slidable valve member 105 over these equalizing ports 103 is arranged to be opened whenever the bridge plug is being traversed through a fluidfilled well bore to enable fluids in the well bore to flow freely through the mandrel bore 104 rather than being forced through the constricted annular space between the casing and the retracted packing means (not shown), Inasmuch as the fishing neck and overshot of the present invention may be employed with any conventional retrievable bridge plug, it is believed unnecessary to devote further attention to the details of the bridge plug.

The overshot 10tl'is operat-ively arranged to be positively secured against rotating relative to the fishing neck 101 whenever the overshot is rotated in one direction. Whenever the overshot is rotated in the opposite direction, however, it is selectively coupled to the fishing neck 101 in such a manner that, by varying the magnitude of applied torque, the overshot is either co-rotatively secured to the fishing neck or is released for rotation relative thereto.

Accordingly, to accomplish these functions, the overshot 100 is comprised of an outer member 106 in which is rotatably mounted an inner coupling member 107 adapted to be engaged over the fishing neck 101. The inner member 107 is selectively coupled to the outer member 106 of the overshot 1% through a first friction clutch 108. arranged in parallel with a second positive driveclutch 109. This second clutch 109 is suitably arranged to be positively engaged in one rotative direction and disengaged in the opposite rotative direction. Thus, whenever the overshot 101i is rotated in the one direction, the friction clutch 108 is inactive since the overshot is co-rotatively secured to the fishing neck .101 through the positively engaged second clutch 109 irrespective of the magnitude of applied torque. On the. other hand, when the overshot 100 is rotated in the opposite direction the second clutch 1119 is no longer effective and the overshot is now corotatively secured to the fishing neck 101 through only the friction clutch 108. This friction clutch 108 is suitably arranged to remain operative until the applied torque reaches a predetermined magnitude. Thereafter, once it releases, the friction clutch 1% will continue slipping so long as the applied torque exceeds this predetermined level to allow the overshot 100 to rotate freely relative to the fishing neck 101.

As seen in FIG. 1, the tubular outer member 106 of the overshot 100 has a reduced diameter bore 110 at its upper end and an enlarged diameter bore 111 at its lower end so as to provide a downwardly facing intermediate shoulder 112 and 2. depending skirt portion 113. The tubular inner member 107 is movably received within the outer member 106 and has an enlarged outer-diameter lower portion 114 with a reduced outer-diameter upper portion 115 that extends upwardly into a downwardly directed annular cavity 116 formed within the intermediate shoulder 112 of the outer member. Opposed lugs 117 projecting inwardly from the inner member 107 are adapted to enter and be received within the open upper ends of longitudinal slots 118 circumferentially spaced around the outside of the fishing neck 101.

The aforementioned friction clutch 108 is comprised of a series of stacked, flat, annular plates 119, 120 that are disposed within the annular clearance space 111 between the skirt portion 113 of the outer member 106 and the reduced-diameter upper portion 115 of the inner member 107. Alternate ones 119 of these plates are slidably mounted and co-rotatively secured to the outer member 106 by longitudinal splines 121 projecting inwardly therefrom; with the remaining plates 120 being co-rotatively secured and slidably mounted to the tubular inner member 107 by external longitudinal splines 122. The stacked clutch plates 119, 1.20 are disposed between an annular lower spacer ring 123 that rests on top of the enlargeddiameter lower portion 114 of the inner member 107 and an annular upper spacer ring 124 resting on top of the stacked plates. A compression spring 125 is disposed within the annular cavity 116 and engaged between a downwardly facing shoulder 126 projecting inwardly from the outer member 106 and the upper face of the upper spacer member 124 to urge the clutch plates 119, 120 into frictional engagement with one another.

It will be appreciated, however, that although the spacer rings 123, 124 and stacked clutch plates 119, 120 are normally urged downwardly by the spring 125 against the enlarged diameter portion 114 of the lower member 107, the lower member is still capable of shifting upwardly a limited distance relative to the outer member 106. It will be realized, of course, that whenever the inner member 107 is urged upwardly, the clutch plates 119, 120 are free to slide along their respective splines 121, 122 until the spring 125 is compressed.

The previously mentioned positively engageable clutch 109 is comprised of an annular member 127 mounted within the skirt portion 113 of the outer member 106 and co-rotatively secured thereto by projecting lugs 128, 129. A plurality of upwardly directed teeth 130 are formed around the upper end of the annular member 127 with one face of each tooth being inclined and the other face being substantially vertical. The compression spring 125 urges the inner member 107 downwardly so that complementary teeth 131 formed around the lower enlargeddiameter portion 114 thereof are normally intermeshed with the teeth 130 on the annular member 127.

Accordingly, it will be seen that, by virtue of the configuration of the teeth 130 and 131, whenever the outer member 106 is rotated in one direction the vertical faces of the teeth will positively engage. Thus, in this one rotative direction, the outer member 106 is positively connected through the teeth 130, 131 to the inner member 107, and from the inner member through lugs 117 to the fishing neck 101.

When the outer member 106 is rotated in the opposite direction, however, the inclined faces of the teeth 130 on the annular member 127 will be driven against the inclined faces of the teeth 131 on the inner member 107. In addition to whatever frictional restraint is provided by the teeth 130, 131, the frictionally engaged clutch plates 119, 120 will co-rotatively secure the outer member 106 to the inner member 107 until this predetermined frictional restraint is overcome. Then, once the plates 119, begin to slide relative to one another, the teeth on the annular member 127 will cam the inner member 107 upwardly relative to the outer member 106 a sufiicient distance to disengage the teeth 130, 131 and allow the outer member to rotate relative to the inner member.

A radially expansible split-nut 132 is received within the lower portion of the skirt 113 beneath the annular member 127 and is co-rotatively secured by lugs 133 to the outer member 106. Upwardly directed teeth 134 within the expansible split-nut 132 are arranged to cooperatively engage complementary downwardly directed teeth 135 around the lower portion of the fishing neck 101. 1

As an added feature, an O-ring 136 cooperatively received in an annular groove around the lower end of the tubular inner member 107 fluidly seals that member to the inside of the outer member 106. A slidable, annular piston member 137 having O-rings 138 and 139 around its outer and inner surfaces, respectively, fluidly seals the upper end 115 of the tubular inner member 107 to the outer member 106. That portion of the annular cavity 116 between the piston member 137 and the lower O-ring 136 is then filled with a suitable hydraulic fluid for lubrication of the clutch plates 119, 120 as well as to prevent the entrance of fluids from the well bore into this space. A lateral port 140 at the upper end of the outer member 106 allows the pressure of the fluids of the well to be imposed upon the upper face of the piston member 137 to eliminate any unbalanced pressure forces on the clutch plates 119, 120'.

Although the equalizing valve shown in FIG. 1 may be arranged in a different manner, the slidable valve member 105 is arranged to be normally biased upwardly by a compression spring (not shown), engaged between the lower end of the valve member and a shoulder (not shown) on the mandrel 102 of the bridge plug. Thus, whenever the overshot 100 has been completely disposed over the fishing neck 101, a downwardly directed shoulder 1411 slightly above the cutting teeth 142 on the overs-hot will engage the upper end of the slidable valve member 105 and force it downwardly to overcome the bias of the spring (not shown) around the mandrel 102. Whenever the overshot is removed, this same spring (not shown) will urge the slidable valve member 105 upwardly to a port-closed position where its upper end engages the lower end 143 of the fishing neck 101.

Thus, it will be appreciated that in one rotative direction, inner and outer members 106, 107 of the overshot 100 are positively engaged by clutch 109. Moreover, when the overshot 100 is rotated in the opposite direction, the outer and inner members 106, 107 of the overshot 100 are frictionally secured to one another through the friction clutch 108. Accordingly, once the cutting teeth 142 on the overshot 100 have cut away sufficient accumulated debris around the upper end of the bridge plug to allow the inwardly projecting lugs 117 to enter the longitudinal slots 118 on the fishing neck 101, the overshot 100 may still be rotated in a predetermined direction by applying sufficient torque thereto to overcome the frictional engagement of the friction clutch 108. Continued rotation of the overshot 100 will, of course, subsequently allow the expansible split-nut 132 to threadedly engage the mating threads 135 around the central portion of the fishing neck 101 and secure the overshot 100 to the fishing neck. It will be realized that should it be unnecessary to rotate the overshot 100 for cutting away any accumulated debris, the split-nut 132 can also be lockingly engaged with the threads 135 on the fishing neck 101 merely by applying a straight downward force to the overshot 100 to ratchet the nut downwardly over the threads 135.

Once the expansible nut 132 has been fully engaged in either manner with the threads 135 of the fishing neck 101, the overshot 100 will have then been lowered a suificient distance over the fishing neck to open the equalizing valve 105 and allow the bridge plug mandrel 102 to be manipulated as necessary to retract the bridge plug and allow it to be retrieved. It will be realized, of course, that the mandrel 102 of the bridge plug may be manipulated in either longitudinal direction, as well as rotated in one direction with any reasonable amount of torque and in the opposite direction with a limited amount of torque.

Turning now to FIG. 2, a typical bridge plug 300 is shown set in place within a cased well bore 301. Elastomeric packing cups 302, 303 are oppositely directed so that one or the other will always be sealingly engaged with the casing 304 whenever there is a pressure differential across the bridge plug 300 from either direction.

Similarly, wall-engaging mean-s such as expanders and slips 305, 306 are oppositely directed so that one set or the other will cooperate to prevent the bridge plug 300 from being shifted by such pressure differentials. An equalizing valve 307 is arranged to function as those previously described in FIG. 1.

A fixed lug 308 projecting inwardly from the housing 30-9 is cooperatively confined within a typically arranged T-shaped slot 310 in the mandrel 311. Whenever the mandrel 311 is to be secured from shifting, the lug 308 is confined Within a short longitudinal slot portion 312; and, to free the mandrel for shifting to actuate either the slips 305 or 306, the mandrel 311 is rotated to pass the lug through a horizontal branch slot portion 313 and into alignment with an elongated longitudinal slot portion 314.

Thus, it will be seen that when the bridge plug 300 is to be retrieved, the mandrel 311 must first be rotated as it is shifted longitudinally to bring the mandrel to a neutral position where the branch slot portion 313 is aligned with the housing lug 300. Then, to resecure the mandrel 311, the mandrel is rotated to shift the elongated slot portion 314 away from the lug 308 and reconfine the lug within the short slot portion 312.

Accordingly, when the overshot 315 and fishing neck 316 depicted in FIG. 3 are arranged as the overshot 100 andfishing neck 101 previously described in conjunction with FIG. 1, the overshot 100 is rotated as it is brought down over the fishing neck 101 to cut away debris therearound. As already described, when the overshot 100 is rotated in a clockwise direction, the clutch 109 is not effective and the overshot is co-rotatively secured to the .fishing neck 101 only through the friction clutch 108 Thus, by applying sufficient torque to overcome the fricplug mandrel 311 to be unjayed during the setting operation. Moreover, when the overshot 100 is to be removed from the fishing neck 101 after the bridge plug 300 has been set, the positive drive of clutch 109 will enable the split-nut 132 to be unthreaded from threads 135 without requiring any particular magnitude of torque.

Also, should any other type of bridge plug require positive drive in one rotative direction, the overshot 100 would provide this ability.

It will be further appreciated that the strength of spring 125 (FIG. 1) governs the frictional restraint of clutch 108. Thus, the restraint needs to he suflicient to allow the bridge plug mandrel 311 to be rotated relative to lug 308 but still not so great that the entire bridge plug 300 will be rotated relative to the casing 304.

Accordingly, it will be appreciated that the above-described em-bodiment illustrates a new improved overshot having various clutching devices provided therewith to enable it to be continually rotated relative to the fishing neck for cutting away accumulated debris above a bridge plug so that the overshot may subsequently be positively re-engaged with the fishing neck on a bridge plug. Moreover, these clutching devices allow the overshot to be selectively secured to the fishing neck so that torque may be applied to a bridge plug mandrel as needed for releasing the bridge plug. Furthermore, these clutching devices enable the overshot to be positively couple to the bridge plug so that the mandrel thereof can be shifted in either longitudinal direction either without or in conjunction with rotation of the mandrel. Thus, it has been shown that with these devices, a positive engagement may be made with a bridge plug without sacrificing the ability to apply positive torque as well as longitudinal forces to the mandrel ot' the bridge plug.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in it broader aspects; and, therefore, the aim of the appended claims is to cover all such changes and modifications as fall Within the true spirit and scope of this invention.

What is claimed is:

1. In apparatus for retrieving a well tool having an upright body and releasably secured in a well bore: a tubular member adapted for connection to a tubing string and having means thereon adapted for removing debris around an upright well-tool body; a coupling member carried by said tubular member and adapted for connection to an upright tool body; first means selectively operable for co-rotatively securing said members upon rotation of said tubular member in one rot-ative direction and releasable upon rotation of said tubular member in the opposite rotative direction; and second means co-rotatively securing said members upon rotation of said tubular member in said opposite direction and releasable at a torque in excess of a predetermined magnitude, whereby said tubular member can be rotated relative to an upright well-tool body.

2. In apparatus for retrieving a well tool having an upright body and releasably secured in a well bore: a cylindrical member adapted for connection to an upright well-tool; a rotatable tubular member adapted for connection to a tubing string and having cutting means thereon adapted for rotatively cutting away debris around an upright welltool body; a rotatable annular coupling member carried within said tubular member and sized and arranged to receive said cylindrical member; means reably securing said coupling member co-rotatively to said cylindrical member; first means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said coupling member to said tubular memher; and second means operable upon rotation of said tubular member in the opposite direction for co-rotatively securing said coupling member to said tubular member and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude, whereby said tubular member can be rotated relative to an upright welltool body.

3. In apparatus for retrieving a well tool having an upright body and releasably secured in a well bore: a cylindrical member adapted for connection to an upright well-tool body; a rotatable tubular member adapted for connection to a tubing string and having cutting means thereon adapted for rotatively cutting away debris around an upright well-tool body, said tubular member having an inwardly directed portion; a rotatable annular coupling member slidably mounted within said tubular member and having a surface opposite to and adapted to engage said inwardly directed portion, said coupling member being sized and arranged to receive said cylindrical member; means releasably securing said coupling member co- Irotatrvely to said cylindrical member; means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said coupling member "-to :said tubular member including co-engageable mating teeth on said inwardly directed portion and'opposed surlface; and frictionally engaged means operable upon ro- 'tation of said tubular member in the opposite rotative direction for co-rotatively securing said coupling member to said tubular member and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude whereby said tubular member can be rotated relative to an upright well-tool body.

4. In apparatus for retrieving a Well tool having an upright body and releasably secured in a well bore: a cylindrical member adapted for connection to an upright well-tool body; a rotatable tubular member adapted for connection to a tubing string and having cutting means thereon adapted for rotatively cutting away debris around an upright well-tool body, said tubular member having an inwardly directed portion; a rotatable annular coupling member slidably mounted within said tubular member and having a surface opposite to and adapted to engage said inwardly directed portion, said coupling member being sized and arranged to receive said cylindrical member; means releasably securing said coupling member co- :rotatively to said cylindrical member; means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said coupling member to said tubular member including co-engageable mating teeth on said inwardly directed portion and opposed surfact; and means operable upon rotation of said tubular member in the opposite rotative direction for co-rotatively securing said coupling member to said tubular mem ber and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude including first and second annular discs having co-engaged surfaces disposed between and respectively co-rotatively secured to said tubular member and coupling member, and spring means urgi'ng said discs into co-engagement.

"e". A well packer sized and adapted for reception in a well bore for packing-d the well bore comprising; a housing member; a body member movably mounted within said housing member; packing means mounted around one of said members and adapted for expansion into sealing engagement with a well bore; wall-engaging means mounted on said housing; means responsive to longitudinal shifting of said body member for extending and holding said wall-engaging means in engagement against a Wall of a well bore; first coupling means releasably securing said body member to said housing member and releasable by rotation of said body member to free said body member for longitudinal shifting; and second coupling means adapted for releasably coupling said body member to a tubing string, said second coupling means including a rotatable tubular member connectable to a tubing string and having cutting means thereon for rotatively cutting away debris around said body member, a rota-table coupling member carried within said tubular member and sized and arranged to operatively engage said body member, means releasably securing said coupling member co-rotatively to said body member, means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said tubular member to said coupling member, and means operable upon rotation of said tubular member in the opposite rotative direction for co-rotatively securing said tubular member to said coupling member and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude.

3 6. A well packer sized and adapted for reception in a well bore for packing-ofl the well bore comprising: a

housing member; a body member movably mounted within said housing member; packing means mounted around 5 one of said member and adapted for expansion into sealing engagement with a Well bore; Wall-engaging means mounted on said housing; means responsive to longitudinal shifting of said body member for extending said wallengaging means into engagement with a Wall of a well bore; first coupling means releasably securing said body member to said housing member and releasable by rotation of said body member to tree said body member for longitudinal shifting; and second coupling means adapted for releasably coupling said body member to a tubing string, said second coupling means including a rotatable tubular member connectable to a tubing string and having cutting means thereon for rotatively cutting away debris around said body member, a rotatable coupling member carried within said tubular member andsized and arranged to operatively engage said body member, means releasably securing said coupling member co-rotatively to said body member, means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said tubular member to said coupling member including co-engageable mating teeth on each of said lastmentioned members, and means operable upon rotation of said tubular member in the opposite rotative direction for co-rotatively securing said tubular member to said coupling member and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude.

7. A well packer sized and adapted for reception in a well bore for packing-off the well bore comprsing: a housing member; a body member movably mounted within said housing member; packing means mounted around one of said members and adapted for expansion into sealing engagement with a Well bore; Wall-engaging means mounted on said housing; means responsive to longitudinal shifting of said body member for extending and holding said wall-engaging means in engagement against a wall of a well bore; first coupling means releasably securing said body member to said housing member and releasable by rotation of said body member to free said body member for longitudinal shifting; and second coupling means adapted for releasably coupling said body member to a tubing string, said second coupling means including a rotatable tubular member connectable to a tubing string and having cutting means thereon for rotatively cutting away diebris around said body member, a rotatable coupling member carried Within said tubular member and sized and arranged to operatively engage said body member, means releasably securing said coupling member co-rotatively to said body member, means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said tubular member to said coupling member including co-engageable mating teeth on each of said last-mentioned members; and means operable upon rotation of said tubular member in the opposite rotative direction for co-rotatively securing said coupling member to said tubular member and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude including first and second annular discs having co-engaged surfaces disposed between and respectively co-rotatively secured to said tubular member and coupling member, and spring means urging said discs into co-engagement.

8. The well packer of claim 7 further including: sealing means fluidly sealing said tubular member to said coupling member for providing a fluid-tight chamber around said annular discs, a hydraulic fluid filling said fluid-tight chamber, and means responsive to well bore pressure for imposing such pressure on said fluid.

9. A well packer sized and adapted for reception in a Well bore for packing-oft the well bore comprising: a housing member; a body member movably mounted Within said housing member; packing means mounted around one of said members and adapted for expansion into sealing engagement with a Well bore; wall-engaging means mounted on said housing; means responsive to longitudinal shifting of said body member for extending and holding said wall-engaging mean-s in engagement against a wall of a well bore; first coupling means releasably securing said body member to said housing member and releasable by rotation of said body member to free said body member for longitudinal shifting and second coupling means adapted for releasably coupling said body member to a tubing string, said second coupling means including a rotatable tubular member connectable to a tubing string and having cutting means thereon for notatively cutting away debris around said body member, a rotatable coupling member carried within said tubular member and sized and arranged to operatively engage said body member, means operable upon rotation of said tubular member for threadedly engaging said tubular member with said body member, means operable upon rotation of said tubular member in one rotative direction for co-rotatively securing said tubular member to said coupling member including eo-engageable mating teeth on each of said last-mentioned members, and means operable upon rotation of said tubular member in the opposite rotative direction for co-rotatively securing said coupling member to said tubular member and selectively releasable upon continued rotation of said tubular member in said opposite direction at a torque in excess of a predetermined magnitude including first and second annular discs having co-engaged surfaces disposed rbetween and respectively oo-rotatively secured to said tubular member and coupling member, and spring means urging said discs into co-engagement.

References Cited by the Examiner UNITED STATES PATENTS 2,762,438 9/1956 Naylor 29486.34 2,804,151 8/1957 Le Bus 175-3l5 X 2,887,162 5/1959 Le Bus 29486.34 2,998,072 8/1961 Cnowe 166-123 3,005,506 10/1961 Le Bus 166-99 X 3,070,170 12/1962 Le Bus et a1 166-99 X CHARLES E. OCONNELL, Primary Examiner. D. H. BROWN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,321,018 May 25, 1967 Howard L. McGilI d that error appears in the above numbered pat- It is hereby certifie and that the said Letters Patent should read as ent requiring correction corrected below.

Column 6, line 47, after "well-tool" insert body column 7, lines 33 and 34, for "surfact" read surface column 8, line 5, for "member" read members line 34, for "comprsing" read comprising line 50, for "diebris" read debris Signed and sealed this 6th day of August 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. IN APPARATUS FOR RETRIEVING A WELL TOOL HAVING AN UPRIGHT BODY AND RELEASABLY SECURED IN A WELL BORE: A TUBULAR MEMBER ADAPTED FOR CONNECTION TO A TUBING STRING AND HAVING MEANS THEREON ADAPTED FOR REMOVING DEBRIS AROUND AN UPRIGHT WELL-TOOL BODY; A COUPLING MEMBER CARRIED BY SAID TUBULAR MEMBER AND ADAPTED FOR CONNECTION TO AN UPRIGHT TOOL BODY; FIRST MEANS SELECTIVELY OPERABLE FOR CO-ROTATIVELY SECURING SAID MEMBERS UPON ROTATION OF SAID TUBULAR MEMBER IN ONE ROTATIVE DIRECTION AND RELEASABLE UPON ROTATION OF SAID TUBULAR MEMBER IN THE OPPOSITE ROTATIVE DIRECTION; AND SECOND MEANS CO-ROTATIVELY SECUR- 